Terahertz near-field probe tip processing method and device

Abstract

The application discloses a method and device for processing a probe tip of a terahertz near-field probe. The method comprises the following steps: a terahertz scanning near-field microscope controls a probe tip to scan a gap on a repair layer; in the scanning process, a wall of the gap hits a side of the probe tip, and a first section and a second section above the first section are formed on the probe tip, a cross-sectional area of the first section gradually decreases from top to bottom, and a maximum cross-sectional area of the first section is smaller than a minimum cross-sectional area of the second section. The application can control the probe tip to scan the gap to change a profile of a side wall of the probe tip in the process of hitting the gap, so that a multi-section probe structure is obtained. The structure can improve a near-field resolution by using a thinner first section, improve a near-field signal-to-noise ratio by using a thicker second section, and better balance the resolution and the near-field signal-to-noise ratio of the probe tip in a terahertz frequency band.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of terahertz near-field imaging, and particularly relates to a processing method and device for a worn and adhered terahertz near-field probe tip. BACKGROUND

[0002] In the process of measuring a sample, the probe tip of a terahertz near-field imaging system will inevitably be worn to a certain extent and become thicker and flatter. According to research, when the probe tip is drawn back and forth across the features of the sample, if the hardness of the probe tip is lower than that of the sample, the material of the probe tip will separate and adhere to the sample, resulting in wear of the probe tip. At the same time, if the contact pressure of the probe tip is in the same order of magnitude as the critical stress of the material of the probe tip, plastic deformation will also occur, causing wear of the tip of the probe tip. In addition to wear, the probe tip used to detect biological samples, such as cells, will also adhere to biological tissues. The combined effect of adhesion and wear will cause the resolution and near-field signal-to-noise ratio of the probe to decrease significantly after more than ten hours of work, and the probe tip cannot be used continuously.

[0003] For probes that cannot be used continuously, known processing methods are relatively high in cost. For example, atomic layer deposition, nanoparticle cleaning agents or ion beam cleaning are used to remove impurities and dirt adhering to the probe; for another example, precise nanomachining tools and techniques are used to repair the surface of the probe. Due to the processing cost, it is usually a choice to discard the probe that cannot be used continuously, but the high price of the probe will increase the cost of near-field detection. SUMMARY

[0004] An object of the present application is to provide a terahertz near-field probe tip processing method. The method scans the gap formed on the repair layer, and uses the impact of the side wall of the probe tip and the gap wall surface to form a thinner first section and a thicker second section from bottom to top. Not only is the surface adhesion of the probe tip removed, but the structure of the processed probe tip can also better balance the resolution and near-field signal-to-noise ratio, thereby improving the near-field signal-to-noise ratio and resolution of the probe and realizing the reuse of the probe tip.

[0005] The above object of the present application is achieved by the following technical solutions:

[0006] The terahertz near-field probe tip processing method comprises the following steps:

[0007] The terahertz scanning near-field microscope controls the probe tip to scan the gap on the repair layer;

[0008] During the scanning process, the wall of the gap hits the side of the probe tip, and forms a first section and a second section above the first section, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section.

[0009] In the technical solution, a commercially available terahertz scanning near-field microscope can be used. The probe tip is installed on a loading table of the terahertz scanning near-field microscope, and the probe tip is operated under the terahertz scanning near-field microscope to scan the repair layer. In one or more embodiments, the morphology of the probe tip can be observed under a light microscope to determine whether the probe tip needs to be processed, for example, the morphology appears thickening, flattening, bending, or the surface adheres to filamentous or particulate impurities; in some preferred embodiments, the probe tip can be controlled to scan a region on the repair layer where no gap is formed, and whether the probe tip needs to be processed or further processed with which gap is determined according to the order of the near-field signal obtained by the terahertz scanning near-field microscope.

[0010] For the probe tip to be processed, the terahertz scanning near-field microscope controls the probe tip to scan the gap on the repair layer. The scanned gap can be a point, for example, the probe tip only moves in the vertical direction, or multiple points, for example, the probe tip is driven by the terahertz scanning near-field microscope to move along a strip-shaped gap, and moves up and down during the movement. When the probe tip scans the gap with a certain amplitude and needle ratio, the side of the probe tip will hit the wall of the gap during the needle movement, and the wall of the gap exerts a reaction force on the side of the probe tip, which not only removes the biological sample adhered to the surface of the probe, but also changes the shape of the probe tip by hitting.

[0011] In the technical solution, the gap hits the side of the probe tip, so that the probe tip can form a desired shape. Specifically, the probe tip includes a second section and a first section from top to bottom, and the first section and the second section can be directly connected or indirectly connected through one or more gradual sections.

[0012] The first section at the lowermost position is used to contact the sample, and during the hitting process, a part of the probe material is ground, and a part of the probe material moves upward to form a gradual section or the lower end of the second section. The cross section of the first section can be a regular structure such as a circle, a rectangle, or a polygon, or an irregular structure, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section, i.e., the end face area of the first section connected with the second section or the gradual section, will be smaller than the minimum cross-sectional area of the second section, i.e., the end face area of the second section connected with the first section or the gradual section.

[0013] The reason for processing the traditional conical probe tip into the above-mentioned desired multi-section structure is that the traditional probe tip with continuously changing diameter needs to balance the resolution and the near-field signal-to-noise ratio: when the probe tip is thinner, the resolution of the terahertz near-field imaging will be improved; and in the excitation process of the terahertz near field, the tip is too sharp to produce a strong local electric field enhancement effect, which causes the electric field to be highly concentrated near the tip, thereby limiting the effective electromagnetic wave coupling between the tip and the sample, and the wave vector matching efficiency and the near-field coupling efficiency are higher at the terahertz frequency under the thicker probe tip. Therefore, it is difficult for the traditional probe tip to simultaneously obtain higher resolution and higher near-field signal-to-noise ratio. This phenomenon is more prominent at the terahertz frequency, and to solve this problem, in the technical solution, the probe tip is processed into a multi-section structure, the first section processed is usually thinner than the tip of the new needle to obtain higher resolution, and the second section processed is usually thicker than the same position of the new needle, which is beneficial to improve the wave vector matching efficiency at the terahertz frequency, and thus improve the near-field signal-to-noise ratio.

[0014] In the technical solution, by the above method, the terahertz scanning near-field microscope can be used to control the probe tip scanning gap to remove the impurities adhered to the surface of the probe tip during the process of the probe tip sidewall moving in the impact gap. The processing cost is low, the operation is convenient, the processing time is shorter, and the surface of the processed probe tip is more flat and regular, which is beneficial to improve the surface quality and performance stability of the probe. In addition, more importantly, the multi-section probe structure obtained by processing can use the thinner first section to improve the near-field resolution and use the thicker second section to improve the near-field signal-to-noise ratio, thereby better balancing the resolution and the near-field signal-to-noise ratio of the probe tip at the terahertz frequency.

[0015] In the present application, a gap processing probe tip of one structure can be used, or probe tips of multiple structures can be used. As a preferred setting mode of the gap structure of the present application, two gap structures of different structures are used to process the probe tip according to the wear and adhesion of the probe tip.

[0016] Specifically, the terahertz near-field probe tip processing method further comprises the following steps:

[0017] The terahertz scanning near-field microscope controls the probe tip to scan the repair layer, and determines the gap of the probe tip scanning based on the order of the collected near-field signal, wherein the gap comprises a first gap and a second gap:

[0018] If the order of the near-field signal is greater than or equal to the first order, the probe tip scans the first gap on the repair layer, and the side surface of the first section formed comprises a plurality of planes;

[0019] If the order of the near-field signal is less than the first order and greater than or equal to the second order, the probe tip scans a second gap on the repair layer, and the side surface of the first segment is curved.

[0020] In the technical solution, the order of the near-field signal of the probe tip with different wear and adhesion conditions is different when imaging. The higher the order of the near-field signal, the more serious the wear degree, and vice versa. Therefore, the probe tip scans the flat surface on the repair layer using the terahertz scanning near-field microscope, which can help the operator to determine the wear condition of the probe tip according to the imaging result. In one or more embodiments, the scanning can be a test point on the surface or a test area.

[0021] When the order of the near-field signal is greater than or equal to the first order, it indicates that the probe tip is seriously worn and the imaging is blurred. For such a probe, the tip has been basically ground and thickened, and is more suitable for the first gap. The cross section of the first gap is preferably a regular shape such as a rectangle or a trapezoid. During the scanning process, the probe tip needs to be scanned at least twice. The first scan is used to form two opposite planes on the first segment, and the second scan is used to form another two opposite planes on the first segment. The four planes together form the rectangular cross section of the first segment.

[0022] When the order of the near-field signal is less than the first order and greater than or equal to the second order, it indicates that the wear degree of the probe tip is relatively light, but it has reached a level that needs to be treated. For such a probe, it is roughly a conical shape, but due to a certain degree of wear and thickening of the surface, it is more suitable for the second gap. The cross section of the second gap is preferably circular. During the scanning process, when the probe tip hits the second gap, the second gap exerts a radial force on the probe tip, so that the side surface of the first segment is curved. Preferably, for the same size of the second gap, one scan is enough.

[0023] When the order of the near-field signal is less than the second order, the wear degree of the probe tip is light, and it does not need to be ground and can continue to be used.

[0024] In some preferred embodiments, for the case where the repair layer is a gold nanometer film, the first order is eight, and the second order is five.

[0025] In the technical solution, the order of the near-field signal is used to determine the wear degree of the probe tip, which can eliminate the influence of subjective judgment when observing with an optical microscope, and more accurately reflect the wear degree of the probe tip. At the same time, according to different wear degrees, the probe tip with heavy wear is scanned multiple times to form the side surface of the first segment, and the probe tip with light wear is scanned once to form the side surface of the first segment, which reduces the probability of breaking or damaging the probe during processing and improves the safety of the probe tip processing.

[0026] In the present application, for the same type of gap, one size of gap processing probe tip can be used, or multiple sizes of gap can be used in sequence to process the probe tip. As a preferred setting mode of the gap size setting of the present application, for the same type of gap, two sizes of gap are used in sequence to process the probe tip to further improve the safety of processing and obtain a second section of thicker, shorter length, and fewer number of gradual change sections of the probe tip, thereby effectively improving the near-field signal-to-noise ratio.

[0027] Specifically, the gap includes a narrow gap with a smaller size and a wide gap with a larger size, and the probe tip first scans the narrow gap on the repair layer and then scans the wide gap on the repair layer.

[0028] In the present technical solution, for the same type of gap, such as a first gap, a first wide gap and a first narrow gap can be set. When the probe tip is controlled to scan, the probe tip first scans the first narrow gap to form a first section, and then scans the first wide gap. Since the first section has been formed when the first narrow gap is scanned, the first wide gap no longer hits the sidewall of the first section when the first wide gap is scanned, but hits the already formed gradual change section and the second section, so that part of the gradual change section is transferred to the second section, and the second section is thicker than when the first narrow gap is scanned.

[0029] If the wide gap is scanned first and then the narrow gap is scanned, the second section is formed first and then the first section is formed, and the first section is more likely to be broken or damaged during processing based on the second section after grinding and reprocessing. Not only that, the first gradual change section is likely to be formed during the formation of the second section, and the second gradual change section is likely to be formed during the formation of the first section, and the increase in the number and length of the gradual change sections is not conducive to the thickening of the second section and the improvement of the near-field signal-to-noise ratio.

[0030] Therefore, compared with the method of scanning the wide gap first and then the narrow gap, the present technical solution uses the narrow gap to form the first section, and in the subsequent scanning of the wide gap, the first section is no longer processed, but part of the material of the gradual change section is extruded to the second section, which not only reduces the probability of damage to the first section and obtains a thinner first section, but also reduces the number and length of the gradual change sections, and the thicker second section further improves the near-field signal-to-noise ratio of the probe tip.

[0031] It is worth noting that the gap size and the scanning method of the gap structure do not conflict. In one or more embodiments, for a cuboid gap, the narrow gap can be scanned several times first to form multiple planes on the side of the first section, and then the wide gap can be scanned several times to form multiple planes on the side of the second section. In one or more embodiments, for a cylindrical gap, a smaller diameter cylindrical gap can be scanned first, and then a larger diameter cylindrical gap can be scanned.

[0032] Further, the diameter or width of the wide gap is 1.2-3 times the diameter or width of the narrow gap. The diameter of the probe to be processed is usually about 100 nm, so the width of the narrow gap should not be too narrow, otherwise the ratio of grinding is too large and the first section is prone to breakage or damage. Preferably, the diameter or width of the narrow gap is 20-35 nm, and further preferably 25-30 nm. Preferably, the diameter or width of the wide gap is 45-60 nm, and further preferably 45-50 nm.

[0033] Further, when scanning the narrow gap, the amplitude of the probe tip is 60-80 nm, and the needle ratio is 35-45%; when scanning the wide gap, the amplitude of the probe tip is 80-150 nm, and the needle ratio is 65-70%. When scanning the narrow gap, the amplitude of the probe tip and the needle ratio need to be controlled relatively smaller, so that the first section is more secure during formation, and at the same time gradually grinds off the excess material on the first section; when scanning the wide gap, the amplitude and the needle ratio of the probe can be appropriately increased for the thicker tapered section and the second section.

[0034] Further, the maximum cross-sectional area of the second section is 2-5 times the minimum cross-sectional area of the first section. In order to better balance the resolution and near-field signal-to-noise ratio, the maximum cross-sectional area of the second section is 2-5 times the minimum cross-sectional area of the first section.

[0035] Further, the length of the first section is 40-100 nm. The length of the first section should not be too long or too short, otherwise it will affect the improvement of the near-field signal-to-noise ratio of the second section, and at the same time, a longer first section is also more prone to breakage or damage.

[0036] Another object of the present application is to provide a terahertz near-field probe tip processing device, which uses an existing terahertz scanning near-field microscope to control the probe tip scanning repair device. During the collision of the probe tip and the repair layer on the repair device, not only the adhesion on the surface is ground off, but also a finer first section and a thicker second section are formed on the probe tip. Compared with the traditional tapered probe tip with continuously changing diameter, the resolution and near-field signal-to-noise ratio can be better balanced.

[0037] The above objects of the present application are achieved by the following technical solutions:

[0038] The terahertz near-field probe tip processing device comprises:

[0039] The terahertz scanning near-field microscope is used to install the probe tip to be processed, and control the gap provided on the repair layer of the probe tip scanning repair device.

[0040] The repair device comprises a repair layer, and a gap is arranged on the repair layer, the gap is used for impacting a probe tip during a probe tip scanning process, and a first section and a second section above the first section are formed on the probe tip, a cross-sectional area of the first section gradually decreases from top to bottom, and a maximum cross-sectional area of the first section is smaller than a minimum cross-sectional area of the second section.

[0041] Further, the gap comprises a cuboid gap and a cylindrical gap, and the gap scanned by the probe tip is determined based on a near-field signal order obtained by scanning the repair layer by the probe tip:

[0042] If the near-field signal order is greater than or equal to a first order, the probe tip scans the cuboid gap;

[0043] If the near-field signal order is less than the first order and greater than or equal to a second order, the probe tip scans the cylindrical gap.

[0044] Further, the gap comprises a narrow gap with a smaller size and a wide gap with a larger size, and a diameter or width of the wide gap is 1.2-3 times of a diameter or width of the narrow gap.

[0045] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0046] 1. The present application can control the gap scanned by the probe tip by using a terahertz scanning near-field microscope, so that the morphology of the side wall of the probe tip changes in the process of impacting the gap, and a multi-section probe structure is obtained, the structure can improve the near-field resolution by using a thinner first section and improve the near-field signal-to-noise ratio by using a thicker second section, and the resolution and the near-field signal-to-noise ratio of the probe tip are better balanced in the terahertz frequency band;

[0047] 2. The present application can effectively remove impurities adhered to the surface of the probe tip, and has the advantages of low processing cost, convenient operation, shorter processing time, smoother and more regular probe tip surface after processing, and improved surface quality and performance stability of the probe;

[0048] 3. The present application uses the near-field signal order to judge the wear degree of the probe tip, can exclude the influence of human subjective judgment when observing by an optical microscope, more accurately reflects the wear degree of the probe tip, and according to different wear degrees, the probe tip with heavy wear is scanned multiple times to form the side surface of the first section gradually, and the probe tip with light wear is scanned once to form the side surface of the first section at one time, thereby reducing the probability of fracture or damage of the probe in the processing process and improving the safety of the probe tip processing;

[0049] 4、The application adopts the first scanning narrow gap to form the first section, and in the subsequent scanning wide gap process, the first section is no longer processed, but the part of the gradual change section material is extruded to the second section, which can not only reduce the probability of damage of the first section, get a finer first section, but also the number of the gradual change section is less, the length is shorter, and the second section is thicker, which will further improve the near-field signal-to-noise ratio of the probe tip;

[0050] 5、The application sets the length of the first section reasonably, which can further improve the processing safety of the first section, and more reasonably set the length and cross-sectional area ratio of the first section and the second section, so as to further obtain a thicker second section on the basis of a finer first section, and improve the resolution and near-field signal-to-noise ratio of the probe tip. BRIEF DESCRIPTION OF DRAWINGS

[0051] The drawings described herein are used to provide further understanding of the embodiments of the application, constitute a part of the application, and do not constitute a limitation on the embodiments of the application. In the drawings:

[0052] Figure 1 It is a flowchart of a probe tip processing method in a specific embodiment of the application;

[0053] Figure 2 It is a flowchart of another probe tip processing method in a specific embodiment of the application;

[0054] Figure 3 It is a flowchart of another probe tip processing method in a specific embodiment of the application;

[0055] Figure 4 It is a structural schematic diagram of a new probe tip (a), a probe tip to be processed (b), and a processed probe tip (c) in a specific embodiment of the application;

[0056] Figure 5 It is a structural schematic diagram of a first repair device in a specific embodiment of the application;

[0057] Figure 6 It is a structural schematic diagram of another first repair device in a specific embodiment of the application;

[0058] Figure 7 It is a structural schematic diagram of a second repair device in a specific embodiment of the application;

[0059] Figure 8 It is a near-field imaging of a probe tip scanning test area to be processed in a specific embodiment of the application;

[0060] Figure 9 It is a near-field imaging of a probe tip scanning test area that completes narrow gap scanning in a specific embodiment of the application;

[0061] Figure 10 To complete the near-field imaging of the test area scanned by the probe tip of the probe in the wide-gap scanning in the specific embodiments of the present application.

[0062] Markings in the drawings and corresponding names of parts:

[0063] 1-first section, 2-gradual change section, 3-second section, 10-substrate, 11-repair layer, 12-first cuboid gap, 121-first longitudinal section, 122-first transverse section, 13-second cuboid gap, 131-second longitudinal section, 132-second transverse section, 14-first cylindrical gap, 15-second cylindrical gap. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with examples and drawings, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and are not as a limitation on the present application.

[0065] In the description of the present application, it is understood that the terms "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0066] Example 1:

[0067] As Figure 1 shown in the terahertz near-field probe tip processing method, comprising the following steps:

[0068] The terahertz scanning near-field microscope controls the probe tip to scan the gap on the repair layer;

[0069] During the scanning process, the wall surface of the gap hits the side surface of the probe tip, and a first section and a second section located above the first section are formed on the probe tip, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section.

[0070] In one or more embodiments, the morphology of the probe tip can be observed under a light microscope to determine whether the probe tip needs to be processed, such as thickening, flattening, bending, or the like, or the surface adheres to filamentous or particulate impurities. In some preferred embodiments, the area on the repair layer where no gap is formed can be controlled by the probe tip, and whether the probe tip needs to be processed can be determined according to the order of the near-field signal obtained by the terahertz scanning near-field microscope.

[0071] In one or more embodiments, the probe tip can be a commonly used platinum-iridium probe, or a metal probe such as gold, silver, carbon nanotube probe, and when the probe tip material has sufficient ductility, the probe tip can be processed by the technical solution. In some embodiments, the repair layer material constituting the gap should have sufficient hardness to reduce the change in the gap width during the impact process. Preferably, the repair layer can be made of gold, and the gap structure can be etched on the gold nanofilm repair layer using electron beam lithography (EBL) or focused ion beam etching (FIB).

[0072] In one or more embodiments, after the scanning is completed, impurities remaining on the gold surface outside the gap can be removed by balloon blowing treatment, acetone or alcohol ultrasonic cleaning, etc.

[0073] In this embodiment, the probe tip is processed into a multi-section structure. The first section processed is usually thinner than the tip of the new needle to obtain higher resolution, and the second section processed fuses part of the probe material from the gradual section and the first section during the impact process, so it is usually thicker than the same position of the new needle, which is beneficial to improve the wave vector matching efficiency in the terahertz band, and further improve the near-field signal-to-noise ratio.

[0074] In some embodiments, the first section and the second section can be directly connected or indirectly connected through one or more gradual sections.

[0075] In some embodiments, the maximum cross-sectional area of the second section is 2-5 times the minimum cross-sectional area of the first section. Preferably, the ratio of the maximum cross-sectional area of the second section to the minimum cross-sectional area of the first section is 10:3-10:4.

[0076] In some embodiments, the length of the first section is 40-100 nm. If the length of the first section is too long or too short, it will affect the improvement of the near-field signal-to-noise ratio of the second section. Meanwhile, a longer first section is also more likely to break or be damaged. Preferably, the length of the first section is 45-55 nm.

[0077] Embodiment 2:

[0078] Based on embodiment 1, the terahertz near-field probe tip processing method as shown in Figure 2 includes the following steps:

[0079] The terahertz scanning near-field microscope controls the probe tip to scan the repair layer, determines the gap of the probe tip scanning based on the order of the collected near-field signals, and the gap includes a first gap and a second gap. When the repair layer is a gold nanofilm:

[0080] If the order of the near-field signal is greater than or equal to eight, the probe tip scans a first gap on the repair layer, and in the scanning process, the wall of the first gap hits the side of the probe tip, and a first section and a second section above the first section are formed on the probe tip, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section, and the side of the first section formed is a plurality of planes.

[0081] If the order of the near-field signal is less than eight and greater than or equal to five, the probe tip scans a second gap on the repair layer, and in the scanning process, the wall of the second gap hits the side of the probe tip, and a first section and a second section above the first section are formed on the probe tip, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section, and the side of the first section formed is a curved surface.

[0082] When the order of the near-field is less than five, the degree of wear of the probe tip is light, and no grinding is required, and the probe tip can continue to be used.

[0083] In some preferred embodiments, the cross section of the first gap is preferably a regular shape such as a rectangle or a trapezoid, and the probe tip needs to be scanned at least twice in the scanning process, the first pass is used to form two opposite planes on the first section, and the second pass is used to form another two opposite planes on the first section, and the four planes together constitute the rectangular cross section of the first section. In one or more embodiments, multiple scans can also be performed, for example, three scans, and the six side planes formed in the three scanning processes together constitute a hexagonal cross section.

[0084] In some preferred embodiments, the cross section of the second gap is preferably a circle, and in the scanning process, when the probe tip hits the second gap, the second gap exerts a force on the probe tip in the radial direction, so that the side of the first section is a curved surface. Preferably, for the same size of the second gap, one scan is sufficient.

[0085] In some embodiments, after a period of scanning processing, the probe tip can be scanned again in the region without a gap, and based on the order of the near-field signal obtained, it is determined whether the probe has reached the desired value, and whether further processing is required.

[0086] In some embodiments, both the gap on the repair layer and the planar region without a gap on the repair layer can be scanned to obtain the order of the near-field signal.

[0087] In some embodiments, the repair layer can also use materials other than gold, and the first order and the second order are selected according to the material used.

[0088] In the embodiment, the degree of wear of the probe tip is determined by the order of the near-field signal, which can exclude the influence of subjective judgment in optical microscope observation, and more accurately reflect the degree of wear of the probe tip. Meanwhile, according to different degrees of wear, the probe tip with heavy wear is processed by multiple scans to form the side surface of the first section, and the probe tip with light wear is processed by single scan to form the side surface of the first section at one time, which reduces the probability of fracture or damage of the probe in the processing process and improves the safety of the probe tip processing.

[0089] Embodiment 3

[0090] Based on the above embodiments, the terahertz near-field probe tip processing method shown in Figure 3 includes the following steps:

[0091] The terahertz scanning near-field microscope controls the probe tip to scan the repair layer, determines the gap of the probe tip scanning based on the collected order of the near-field signal, and the gap includes a first gap and a second gap. When the repair layer is a gold nano film:

[0092] If the order of the near-field signal is greater than or equal to eight, the probe tip scans the first gap on the repair layer. In the scanning process, the first narrow gap is scanned first, and then the first wide gap is scanned. The wall surface of the gap hits the side surface of the probe tip, and a first section and a second section located above the first section are formed on the probe tip. The cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section. The side surface of the formed first section includes multiple planes.

[0093] If the order of the near-field signal is less than eight and greater than or equal to five, the probe tip scans the second gap on the repair layer. In the scanning process, the second narrow gap is scanned first, and then the second wide gap is scanned. The wall surface of the gap hits the side surface of the probe tip, and a first section and a second section located above the first section are formed on the probe tip. The cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section. The side surface of the formed first section is a curved surface.

[0094] In the embodiment, the first section is formed by scanning the narrow gap first, and in the subsequent scanning of the wide gap, the first section is no longer processed, but part of the material of the gradual section is extruded to the second section. This not only reduces the probability of damage to the first section and obtains a finer first section, but also reduces the number and length of the gradual section, and the second section is thicker, which further improves the near-field signal-to-noise ratio of the probe tip.

[0095] In some preferred embodiments, the diameter or width of the wide gap is 1.2-3 times the diameter or width of the narrow gap. Preferably, the diameter or width of the narrow gap is 20-35 nm, and more preferably 25-30 nm. Preferably, the diameter or width of the wide gap is 45-60 nm, and more preferably 45-50 nm.

[0096] In some preferred embodiments, when scanning the narrow gap, the amplitude of the probe tip is 60-80 nm, and the down needle ratio is 35-45%; when scanning the wide gap, the amplitude of the probe tip is 80-150 nm, and the down needle ratio is 65-70%.

[0097] In some embodiments, the repair layer can also be made of materials other than gold, and the first order and the second order are selected according to the material used.

[0098] Embodiment 4:

[0099] A terahertz near-field probe tip processing device, comprising:

[0100] A terahertz scanning near-field microscope for mounting a probe tip to be processed, and controlling the probe tip to scan a gap provided on a repair layer of a repair device;

[0101] A repair device comprising a repair layer, wherein the repair layer is provided with a gap for impacting a probe tip during scanning of the probe tip, and forming a first section and a second section above the first section on the probe tip, wherein the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section.

[0102] In some embodiments, as shown in Figure 5 , the repair device can use a silicon substrate 10, and a layer of gold nanometer film is processed on the surface of the silicon substrate as a repair layer 11, and then EBL or FIB is used to etch the required gap structure on the gold nanometer film repair layer. In one or more embodiments, as shown in Figure 5 and Figure 6 , the electron beam can be controlled to move in a specific direction to etch one or more cuboid gaps on the gold nanometer film. In one or more embodiments, as shown in Figure 7 , the electron beam can be controlled to etch a cylindrical gap at a specified position.

[0103] In some embodiments, the cuboid gap can include mutually perpendicular transverse sections and longitudinal sections, such as the first longitudinal section 121, the first transverse section 122, the second longitudinal section 131, and the second transverse section 132 as shown in Figure 6 , so that the repair device does not need to be adjusted, and only the probe tip needs to be controlled to scan down the transverse sections and the longitudinal sections in sequence, so that multiple planes can be formed on the side surface of the first section.

[0104] In some embodiments, the cuboid gap and the cylindrical gap can be arranged on the same repair layer or on different repair layers.

[0105] In some embodiments, the gap comprises a cuboid gap and a cylindrical gap, the gap for the probe tip scanning is determined based on the order of the near-field signal obtained by the probe tip scanning the repair layer, and when the repair layer is a gold nano-film:

[0106] If the order of the near-field signal is greater than or equal to eight, the probe tip scans the cuboid gap as shown in Figure 5 and Figure 6 .

[0107] If the order of the near-field signal is less than eight and greater than or equal to five, the probe tip scans the cylindrical gap as shown in Figure 7 .

[0108] In some preferred embodiments, the gap comprises a narrow gap with a smaller size and a wide gap with a larger size, and the diameter or width of the wide gap is 1.2 to 3 times the diameter or width of the narrow gap.

[0109] Example 5:

[0110] The platinum-iridium probe tip to be processed is loaded on the loading table of the terahertz near-field scanning microscope, and the needle is lowered by conventional operation. First, the probe tip is hit on the strip-shaped gap on the repair layer, and the light path and the sample area are adjusted to achieve the best signal. The imaging of the test area on the gold surface is as shown in Figure 8 , and the boundary between the gap and the plane is blurred. At the same time, the order of the near-field signal is greater than eight, indicating that the probe tip is severely worn. For such a probe tip, considering the safety and stability of the probe tip during processing, a cuboid gap is used as the first gap to process the probe tip.

[0111] A 50-nm-thick gold nano-film is processed on a silicon substrate, and a first cuboid gap 12 and a second cuboid gap 13 with widths of 30 nm and 50 nm, respectively, are etched on the surface of the film by using an electron etching process.

[0112] The amplitude of the probe tip is adjusted to 70 nm by adjusting the piezoelectric voltage of the probe tip, and the needle lowering ratio is set to 40%. The scanning is performed along the first cuboid gap, which can alternately pass through the horizontal section and the vertical section, or the horizontal section is scanned first and then the vertical section is scanned. The scanning is repeated for 3 to 4 times. The imaging of the test area on the gold surface is as shown in Figure 9 , and Figure 8 It can be seen that the boundary between the gap and the plane is relatively clear, but it is still difficult to distinguish.

[0113] Next, by adjusting the piezoelectric voltage of the probe tip to make the amplitude of the tip 120 nm, setting the down needle ratio to 70%, the second cuboid gap is operated by the down needle, which can alternately pass through the horizontal section and the longitudinal section, or first scan the horizontal section, then scan the longitudinal section, and repeat the scanning 3-4 times, and finally obtain a first section and a second section, and the side surface of the first section has a plurality of planes. The imaging of the test area on the gold surface is shown in Figure 10

[0114] Example 6

[0115] The platinum-iridium tip to be processed is loaded on the loading table of the terahertz near-field scanning microscope, and the down needle is operated in a conventional manner. First, the probe tip is hit on the gold surface test area on the repair layer, the light path and the sample area are adjusted to achieve the best signal, and the near-field signal order is observed to be greater than five and less than eight, indicating that the probe tip is lightly worn. For such a tip, a cylindrical gap is used as a second gap to process the probe tip.

[0116] A 50nm-thick gold nanofilm is processed on a silicon substrate, and a first cylindrical gap 14 and a second cylindrical gap 15 with diameters of 30nm and 50nm respectively are etched on the surface of the thin film by using an electron etching process.

[0117] By adjusting the piezoelectric voltage of the probe tip to make the amplitude of the tip 60 nm, setting the down needle ratio to 40%, the first cylindrical gap is operated by the down needle, and the operation is repeated 3-4 times. Next, by adjusting the piezoelectric voltage of the probe tip to make the amplitude of the tip 130 nm, setting the down needle ratio to 70%, the second cylindrical gap is operated by the down needle, and the operation is repeated 3-4 times, and finally obtain a first section and a second section, and the side surface of the first section is a curved surface.

[0118] Although the embodiments of the present application only show two structures of cuboid gap and cylindrical gap, those skilled in the art should understand that there can be other structures of gaps, such as conical gap, gap with trapezoidal cross section, etc., which should also be included in the protection scope of the present application.

[0119] In the present application, "first", "second", etc. (such as first section, second section, first cuboid gap, second cuboid gap, etc.) are only used to distinguish the corresponding parts for the sake of clarity, and are not intended to limit any order or emphasize importance. In addition, the term "connection" used in the present application can be direct connection or indirect connection via other components without special description.

[0120] ​The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of processing a tip of a terahertz near-field probe, characterized by, The method comprises the following steps: The method comprises the following steps: The walls of the gap hit the side of the probe tip during scanning and form a first section on the probe tip and a second section above the first section, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section. The first section is thinner than the tip of the new needle, and the second section is thicker than the same position of the new needle. The method further comprises the following steps: The method further comprises the following steps: If the order of the near-field signal is greater than or equal to the first order, the probe tip scans a first gap on the repair layer, and the side of the first section formed includes multiple planes. If the order of the near-field signal is less than the first order and greater than or equal to the second order, the probe tip scans a second gap on the repair layer, and the side of the first section formed is a curved surface.

2. The method of claim 1, wherein The gap includes a narrow gap with a smaller size and a wide gap with a larger size, and the probe tip scans the narrow gap on the repair layer first and then scans the wide gap on the repair layer.

3. The method of claim 2, wherein the method further comprises: The diameter or width of the wide gap is 1.2-3 times the diameter or width of the narrow gap.

4. The method of claim 2, wherein the method further comprises: When scanning the narrow gap, the amplitude of the probe tip is 60-80 nm, and the down-needle ratio is 35-45%; when scanning the wide gap, the amplitude of the probe tip is 80-150 nm, and the down-needle ratio is 65-70%.

5. The terahertz near-field probe tip processing method according to any one of claims 1 to 4, characterized by, The maximum cross-sectional area of the second section is 2-5 times the minimum cross-sectional area of the first section.

6. The terahertz near-field probe tip processing method according to any one of claims 1 to 4, characterized by, The length of the first section is 40-100 nm.

7. A terahertz near-field probe tip processing apparatus, characterized by, The processing device for the terahertz near-field probe tip in claim 1 comprises: A terahertz scanning near-field microscope is used to install the probe tip to be processed and control the probe tip to scan the gap provided on the repair layer of the repair device. The repair device comprises a repair layer, and the repair layer is provided with a gap for hitting the probe tip during scanning of the probe tip and forming a first section on the probe tip and a second section above the first section, the cross-sectional area of the first section gradually decreases from top to bottom, and the maximum cross-sectional area of the first section is smaller than the minimum cross-sectional area of the second section. The first section is thinner than the tip of the new needle, and the second section is thicker than the same position of the new needle.

8. The terahertz near-field probe tip processing apparatus according to claim 7, wherein The gap includes a rectangular gap and a cylindrical gap, and the order of the near-field signal obtained by scanning the repair layer by the probe tip is used to determine the gap scanned by the probe tip: If the order of the near-field signal is greater than or equal to the first order, the probe tip scans the rectangular gap. If the order of the near-field signal is less than the first order and greater than or equal to the second order, the probe tip scans the cylindrical gap.

9. The terahertz near-field probe tip processing apparatus according to claim 7, wherein The gap includes a narrow gap with a smaller size and a wide gap with a larger size, and the diameter or width of the wide gap is 1.2-3 times the diameter or width of the narrow gap.

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